The overall goal of this project is to determine the specificity, distribution, and function of Tcells bearing the newly described T cell receptor comprising the gamma:delta heterodimer associated with CD3, which we refer to as TCR1. Our working hypothesis is that TCR1 is specific for class I MHC gene products distinct from conventional class I genes in the murine MHC (class IB), and that their principal role is surveillance of the integrity of epithelial cell membranes. To test this hypothesis, the following experiments will be carried out: Intraepithelial lymphocytes will be isolated and tested for expression of mRNA encoding TCR genes, and for surface expression of TCR protein by precipitation with anti-CD3 or anti-TCR antibodies, and by immunofluorescence for cell surface phenotype and receptor expression where reagents are available. Isolated TCR1-bearing T cells will be stimulated with antigen or with anti-receptor antibody, propagated in IL-2, and cloned and/or hybridized to TCR-negative T lymphoma cells to provide a stable source of TCR1 bearing T cells. The function of freshly isolated TCR1 bearing T cells or of cloned lines or hybrids will be studied using anti-CD3 antibody as a mock ligand. The activation requirements of resting as well as cloned TCR1 bearing T cells will be studied, as will the production of lymphokines and the response to lymphokines of these cells. Finally, these cells will be used to determine the ligand specificity of TCR1 bearing T cells isolated from epithelia, by stimulation with L cells transfected with various MHC genes. If such a gene does activate a TCR1 bearing cell, its expression in normal, infected and transformed cells of that tissue will be examined to determine if differential expression of that gene could account for TCR1-mediated epithelial surveillance.